A massed production method for solid state tantalum capacitors is described in U.S. Pat. No. 5,357,399 (inventor Ian Salisbury). This method involves providing a substrate wafer of solid tantalum, forming a sintered, highly porous, layer of tantalum on the substrate, sawing the layer of porous tantalum with an orthogonal pattern of channels to produce an array of upstanding porous tantalum rectilinear bodies, anodising the bodies to form a dielectric layer thereon, dipping the bodies in manganese nitrate solution and heating to convert the applied solution to manganese dioxide thereby to form a cathode layer, applying respective conducting layers of carbon and then silver onto top ends of each body, bonding a lid consisting of a wafer of solid metal onto the silver layer; injecting insulating resin material into the channels between bodies constrained by the substrate and lid; and slicing the assembly in a direction perpendicular to the plane of the wafers and along the centre line of each channel thereby to produce a plurality of capacitors in which the anode terminal consists of substrate material, the cathode terminal consists of lid material and the capacitive body consists of the coated porous tantalum body.
Our pending application PCT/GB99/03566 (corresponding to UK application number 9916047.5), describes a variation on the Salisbury method, in which the lid layer is omitted. In capacitors manufactured according to this method the volumetric efficiency of each capacitor produced is maximized.